1. Field of the Invention
This invention relates generally to the field of exploration and production of hydrocarbons. More specifically, the invention relates to apparatus and methods for deploying equipment such as natural gas processing systems at the wellsite.
2. Background of the Technology
Unprocessed natural gas in its native form contains varying percentages of the following components: hydrogen sulfide; carbon dioxide; lower aliphatic hydrocarbons such as methane, ethane, propane, butane, pentane, and hexane; small amounts of aliphatic hydrocarbons having more than six carbon atoms; water vapor; nitrogen; and trace amounts of gases such as mercaptans, carbonyl sulfide, helium and argon. In addition, during the drilling and initial flow of natural gas from wells, fluids such as drilling muds, fraccing fluids, carbon dioxide, and methanol may be introduced to improve flow and life of the wells. To be commercially acceptable, produced natural gas in its native form must undergo processing to remove many of the components, other than methane, in order to meet stringent specifications with respect to heating value and the content of certain components prior to introduction to commercial pipelines. For example, a sufficient amount of hydrogen sulfide must be removed from the natural gas so that the processed gas product has a hydrogen sulfide concentration of less than about 0.25 to 0.5 grains per 100 standard cubic feet. Further, the carbon dioxide content of the processed gas product should be less than about two mole percent (4 wt %) since higher concentrations can be corrosive. Removal of carbon dioxide from the produced gas is also preferable since its presence reduces the heating value of the natural gas.
Produced natural gas may be processed at the wellsite (i.e., at the location of the well from which the natural gas was produced) or transported from the wellsite in its native form, along with produced natural gas from other wellsites, to a centralized gas processing facility. Some types of processing systems and methods commonly employed in the controlled environment of a central processing facility are not designed or suitable for use at remote wellsite locations. Accordingly, systems and methods for processing natural gas at the wellsite require consideration of a multitude of factors that are unique to on-site processing. For example, some wellsites are located in remote areas which are not readily accessible and have no on-site operating personnel. As another example, many wellsites are located in geographical areas subject to extreme changes in climatic conditions from a winter period with ice, snow and extremely low temperature conditions (e.g., 32° F. to −50° F.) to a summer period with extremely high temperature conditions (e.g., 90° F. to 120° F.). While environmental conditions may be controlled at a central processing facility, environmental conditions at remote wellsites are generally uncontrollable, and thus, processing and production equipment at the wellsites are subject to extreme conditions without the advantage of constant on-site maintenance and operating service personnel.
Another consideration for on-site processing systems is the need for ease of transportation and deployment. As previously described, due to the remote locations of some wellsites, simply getting the processing equipment to the wellhead in a safe and efficient manner may be challenging. For many on-site applications, the need for the specific processing equipment only lasts for a relatively short period of time as compared to the total production time. Consequently, it is often desirable to periodically relocated processing equipment between different wellsites. Most conventional on-site gas processing systems are loaded and unloaded from a transport vehicle (e.g., tractor trailer) with a crane or are permanently located on trailers. Thus, a crane must be acquired or rented, and transported to the wellsite along with the gas processing equipment. In addition, during the initial stages of preparing for production, fracturing operations, and initial flow back, wellsites are typically congested with drilling and fracturing equipment. Consequently, there may be limited space for locating and operating a crane to load and unload the gas processing equipment at the wellsite. Moreover, locating wheeled transportation within a congested site may lead to additional issues as well as safety issues related to accessing and leaving raised trailer mounted equipment.
Accordingly, there remains a need in the art for apparatus and systems for deploying equipment such as gas processing systems at remote wellsites which offer the potential to reduce and/or eliminate the issues described above. Such systems and methods would be particularly well-received if they did not require additional equipment and associated costs to deploy the equipment at the wellsite.